Are sea levels really rising?

The Earth’s oceans have been rising over the past century, and the rate of this rise has increased in recent decades. There are two primary causes of global sea level rise: thermal expansion caused by warming of the ocean and increased melting of land-based ice, such as glaciers and ice sheets. What does the evidence say?

Evidence of Sea Level Rise

• Tide Gauge Records: Tide gauges measure sea levels relative to a fixed point on land. Records from these gauges show an average global sea level rise of 8-9 inches (21-24 centimeters) since 1880. Data from the Permanent Service for Mean Sea Level (PSMSL) provides evidence of rising sea levels, with an average rate of 1.7 mm/yr over the 20th century.
• Satellite Altimetry: Satellite altimetry measures sea levels using radar altimeters. Since 1993, satellites have provided a precise record of sea level changes, showing an average rise of 3.2 mm (0.13 inches) per year. This rate has accelerated to 4.62 mm (0.182 inches) per year for the decade 2013-2022.
• Ocean Heat Content: The ocean absorbs more than 90% of the increased atmospheric heat associated with greenhouse gas emissions. This heat causes the ocean water to expand, contributing to sea level rise.
• Melting Glaciers and Ice Sheets: Glaciers and ice sheets worldwide are losing mass at an accelerating rate. Greenland’s ice sheet, for example, has contributed significantly to sea level rise, with an average annual ice loss of 3,902 gigatons between 1992 and 2018.
• Sea Level Rise Acceleration: The rate of sea level rise is accelerating. Between 2006-2015, the global mean sea level rose by 0.14 inches (3.6 millimeters) per year, which is 2.5 times the average rate of 0.06 inches (1.4 millimeters) per year throughout most of the 20th century ¹ ².

Consequences of Sea Level Rise

• Coastal Flooding and Erosion: Rising sea levels lead to more frequent and severe coastal flooding, erosion, and saltwater intrusion into freshwater sources.
• Displacement and Migration: Sea level rise poses a significant threat to coastal populations, with estimates suggesting that 150 million people could be displaced by 2050.
• Economic Impacts: Sea level rise can damage infrastructure, disrupt trade, and impact tourism and recreation.

Is There Evidence that Sea Levels Are Not Rising?

There is no credible evidence to suggest that sea levels are not rising. The overwhelming scientific consensus supports the fact that sea levels are rising due to human-caused climate change. While natural variability in sea levels exists, the current rate of rise is unprecedented over the past 2,500-plus years.

Some arguments against sea level rise might point to:

• Regional Variations: Sea level rise is not uniform globally. Regional differences exist due to natural variability in ocean currents, wind patterns, and land processes.
• Short-Term Fluctuations: Sea levels can fluctuate over short periods due to events like El Niño or La Niña. However, these fluctuations do not negate the long-term trend of rising sea levels.

Future Projections

• Sea Level Rise by 2100: Projections suggest that global sea levels could rise by 28-61 cm (11-24 inches) by 2100 under a low-emissions scenario and 52-98 cm (20-39 inches) under a high-emissions scenario.
• Long-Term Commitment: Even if greenhouse gas emissions are reduced, sea levels will continue to rise for many centuries due to the slow response of the climate system ² ¹.

The evidence for sea level rise is clear and compelling. Human-caused climate change is driving the rise in sea levels, and the consequences of this rise will be far-reaching and devastating if left unchecked. Understanding the causes and impacts of sea level rise is crucial for developing effective strategies to mitigate and adapt to this pressing global issue.

Advertisement:

No products found.